Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the annotations, it discloses that the coupon is live at checkout immediately, that confirmation applies by default with an opt-out, and that the call reaches other people so user confirmation is needed. The auth requirement (Cotlet API key with app access) is also stated. The confirmation wording is slightly muddled but adds real behavioral context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

It front-loads the coupon scope, which is good, but the remaining content is a run-on covering discount math, per-buyer guidance, confirmation policy, and auth. The two adjacent confirmation sentences overlap and read as slightly contradictory, hurting structure.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a creation tool with no output schema, the description covers scope, discount behavior, side effects, confirmation, and auth needs. It lacks any mention of the resulting coupon code/response, but that gap is minor given the tool's low output complexity.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all nine parameters, establishing a baseline of 3. The description adds discount semantics (percentage applies to original price, fixed is deducted) and the per-buyer-limit behavior, which is modest extra value over the enum descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description makes clear this is about a Payhip coupon code scoped to a whole order, single product, or collection, and names the discount mechanics. The creating action is implied by the name/title rather than stated as a verb in the text, and no sibling (e.g., payhip_list_coupons) is named for contrast, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives a genuine usage hint – Payhip has no per-buyer limit, so a product-specific or single-use code is the workaround – which steers behavior. However it never states when to reach for this tool versus list_coupons or update, so routing guidance is only partial.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.